Catamaran



June 19, 1962 A. N. DUCOMMUN 3,

CATAMARAN Filed Jan. 11, 1960 &

flL/Q/V /V. QZ/COMMZ/M IN V EN TOR.

,4 TTQQ/VEVS United States Patent v 3,039,416 CATAMARAN Alan N.Ducommun, 1 Maverick Lane, Rolling Hills, Calif. Filed Jan. 11, 1960,Ser. No. 1,630 9 Claims. (Cl. 11461) This invention relates to twin hullvessels, sometimes known as catamarans, and is particularly directed toan improved form of linkage which joins the two hulls and supports aplatform between them so that the entire assembly can serve as asailboat or a powerboat.

In conventional catamaran construction, the two hulls are rigidly fixedtogether. In such devices, severe racking stresses are imposed upon thestructure when a quartering wave lifts either the front or the rear ofone of the hulls. In this situation, the other hull must be dragged upfrom the water until its position corresponds with that of the firsthull, or else the whole structure must twist. The net effect is thatwhenever either hull meets a wave it will be forced below its normallevel of flotation until its total flotation force is suflicient to liftthe other hull above its normal position in the water. The entirestructure therefore is subjected to continuous twisting and rackingforces unless the water level for both floats is identical.

While attempts have been made to connect the twin hulls of catamarans ina manner so that the hulls may have limited relative motion, suchdevices have met with very little success. When flexible connectingstructure has been used, the twisting and racking stresses imposed onsuch structure lead to early failure. When stiff cross members withflexible connections to the hull have been used, the connecting partshave had very short lives and the hulls have not been prevented fromhaving relative rolling movement. Relative rolling movement of the hullsis particularly objectionable when sails provide the motive power,because such a structure lacks the necessary stability about thelongitudinal axis to resist the overturning moment of the sails.

It is an important object of this invention to provide an improved formof apparatus for connecting the twin hulls of a catamaran in order toavoid the shortcomings pointed out above.

Briefly stated, this invention concerns a twin hull structure having apair of connector assemblies extending between the hulls, one of theconnector assemblies permitting relative pitching motion of the hullsbut preventing relative rolling movement thereof, and the otherconnector assembly comprising a spacer strut connected to the hulls byself-aligning parts. Another feature of the invention concerns a centralplatform member mounted on the first connector assembly and having apart slidably guided with respect to a longitudinal projection on thespacer strut. Another feature of the invention concerns the provision ofa longitudinal torsion bar operatively interposed between the centralmember and the spacer strut acting resiliently to oppose relativepitching motion of the two hulls.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIGURE 1 is a top plan view in diagrammatic form showing a preferredembodiment of this invention.

FIGURE 2 is a longitudinal sectional view taken substantiallyon thelines 22 as shown in FIGURE 1.

FIGURE 3 is a transverse sectional view taken substantially on the lines33 as shown in FIGURE 2.

FIGURE 4 is a transverse sectional view taken substantially on the lines44 as shown in FIGURE 2.

FIGURE 5 is a sectional view taken substantially on the lines 5-5 asshown in FIGURE 2.

3 ,03 9,416 Patented June 19, 1962 Referring to the drawings, the twinhulls or pontoons 10 and 11 are substantially parallel and are laterallyspaced. A first connector assembly 12 extends horizontally between thehulls 10 and 11 and supports one end of a platform member 13 positionedbetween the hulls. A second connector assembly 14 longitudinally spacedfrom the connector assembly 12 extends transversely between the hulls 10and 11.

As best shown in FIGURE 3, the first connector assembly 12 includes apair of axially aligned axles or trunnions 15 and 16. Bearing housings17 and 18 fixed to the platform member 13 support the trunnions 15 and16 respectively for relative turning movement. An element 19 fixed onthe hull 10 is connected by vertical pivot pin 20 to a projectingportion of the trunnion 15. Similarly, the element 22 fixed to the hull11 is connected by vertical pivot pin 21 to the projecting portion ofthe trunnion 16. From this description it will be understood that thefirst connector assembly 12 permits the bulls 10 and 11 to have relativepitching movement about the common axis of the trunnions 15 and 16, andto have pivotal movement about the pins 20 and 21, but relative rollingmotion of the hulls 10 and 11 about longitudinal axes is prevented.

As best shown in FIGURE 5, the second connector as sembly 14 includes aspacer strut 25 connected by flexible joints 26 and 27 to elements 28and 29 respectively fixed on the hulls 10 and 11. Th flexible joints 26and 27 may take the form of gimbal rings or universal joints, or maycomprise ball-and-socket connections. The strut 25 is preferably tubularin form for minimum weight and maximum stiffness.

It will be observed that when the hulls have relative pitching motionabout the common axis of the trunnions 15 and 16 that the spacer strut25 moves from horizontal to inclined position, thereby slightly reducingthe horizontal spacing between the hulls from the first connectorassembly'12 back toward the second connector assembly 14 and increasingthe horizontal spacing forward of the first connector assembly 12. Thismotion is accommodated by movement of the parts about the vertical pins20 and 21.

A longitudinal tubular post 31 is fixed centrally to the spacer strut 25by any convenient means. As shown in the drawings, this longitudinalpost 31 is fixed to a split sleeve 32 clamped to the outer surface ofthe strut 25 by means of the threaded fastening 33'. The post 31 isslidably received within the bore 34 of the socket member 35. Thissocket member 35 is fixed to the platform member 13 by any convenientmeans such as, for example, by the threaded fasteners 36. From thisdescription it will be understood that the post 31 assists in supportingthe platform member 13 and that the post 31 turns with respect to thesocket member 35 upon relative pitching movement of the hulls 10* and11.

Means are provided for resiliently opposing relative pitching movementof the hulls 10 and 11 about the common axis of the trunnions 15 and 16,and as shown in the drawings, this means includes a longitudinal torsionbar 40 positioned between the hulls and under the platform member 13.The forward end of this torsion bar is fixed by means of a set screw 41within bracket 42 fixed to the underside of the platform member 13. Thebar may be hexagonal in form and extends slidably through a hexagonalopening 43 in an internal collar 44 fixed within the tubular post 31.When the tubular post 31 and collar 44 turn with the spacer strut 25,the effect is to twist the torsion bar 40, and this action resilientlyopposes relative pitching movement of the hulls 10 and 11.

The linkage provided by the first and second connector assemblies andcentral platform member permits the two hulls to move independently in afairly extended range. The vertical hinge pins 21) and 21 aiford thefull resistance of the two widespread hulls to oppose any overturn ingmoment of a sail about the longitudinal axis of the craft. The universaljoints 26 and 27 and the hinge pins 20 and 21 make the craftcomparatively easy to disassemble for hauling, beaching or repair.

Having fully described my invention it is to be understood that I am notto be limited to the details herein set forth but that my invention isof the full scope of the appended claims.

I claim:

1. In a catamaran, the combination of: twin hulls; first and secondconnector assemblies extending between said hulls; said first connectorassembly having axially aligned trunnions each connected by means of avertical pivot to one of the hulls, respectively, and mounting means forsaid trunnions whereby the hulls are permitted to have relative pitchingmovement and are prevented from having substantial relative rollingmovement; said second connector assembly having a transverse spacerstrut, and universal joint means connecting the ends of said strut tosaid hulls; a central member supported upon said trunnion mountingmeans; and a longitudinally extending part on said strut slidablyconnected to a cooperating part on said central member.

2. In a catamaran, the combination of: twin hulls; first and secondconnector assemblies extending between said hulls; said first connectorassembly having axially aligned trunnions each connected by means of avertical pivot to one of the hulls, respectively, and mounting means forsaid trunnions, whereby the hulls are permitted to have relativepitching movement and prevented from having substantial relative rollingmovement; said second connector assembly having a transverse spacerstrut, and universal joint means connecting the ends of said strut tosaid hulls; a central member supported upon said trunnion mountingmeans; and means including a torsion bar extending parallel to saidhulls connecting said strut and said central member and actingresiliently to oppose relative pitching movement of said hulls.

3. In a catamaran, the combination of: twin hulls; first and secondconnector assemblies extending between said hulls; said first connectorassembly having axially aligned trunnions each connected by means of avertical pivot to one of the bulls, respectively, and mounting means forsaid trunnions, whereby the hulls are permitted to have relativepitching movement and prevented from having substantial relative rollingmovement; said second connector assembly having a transverse spacerstrut, and universal joint means connecting the ends of said strut tosaid hulls; a central member supported upon said trunnion mountingmeans; a tubular post extending longitudinally on said strut, a socketmember on the central member slidably receiving said post; and meansincluding a torsion bar extending within the tubular post connectingsaid post and said central member and acting resiliently to opposerelative pitching movement of said hulls.

4. In a catamaran, the combination of: a pair of longitudinallyextending laterally spaced horizontal hulls; first and second laterallyextending longitudinally spaced connector assemblies extendinghorizontally between said hulls; said first connector assembly includinga pair of trunnions mounted for relative turning movement about a commonhorizontal axis extending transversely of the hulls, a pair of elements,one fixed to each hull, respectively, pivot means connecting eachtrunnion to one of said elements, respectively, for pivotal movementabout vertical axes, whereby said hulls may have relative pitchingmovement about said common transverse axis of said trunnions as well asrelative movement about said pivotal axes but are held againstsubstantial relative rolling motion; said second connector assemblyincluding a transverse spacer strut, a pair of elements, one fixed toeach hull, respectively, universal joints connecting the ends of saidstrut to the latter said elements, a central member provided forsupporting said trunnions for relative turning movement, and wherein alongitudinally extending part on said spacer strut is slidably receivedin guided relationship with a cooperating part on said central member.

5. The combination as set forth in claim 4 wherein the saidlongitudinally extending part on said spacer strut is slidably receivedwithin a socket member on said central member.

6. Linkage for connecting twin hulls of a catamaran, comprising, incombination: first and second laterally extending longitudinally spacedconnector assemblies adapted to extend horizontally between the hulls;said first connector assembly including a pair of trunnions mounted forrelative turning movement about a common horizontal axis extendingtransversely of the bulls, a pair of elements, one adapted to be fixedto each hull, respectively, pivot means connecting each trunnion to oneof said elements, respectively, for pivotal movement about verticalaxes, said second connector assembly including a transverse spacerstrut, a pair of elements, one adapted to be fixed to each hullrespectively, universal joints connecting the ends of said strut to thelatter said elements, respectively, a central member provided forsupporting said trunnions for relative turning movement, and wherein alongitudinally extending part on said spacer strut is slidably receivedin guided relationship with a cooperating part on said central member.

7. Linkage for connecting twin hulls of a catamaran, comprising, incombination: first and second laterally extending longitudinally spacedconnector assemblies adapted to extend horizontally between the hulls;said first connector assembly including a pair of trunnions mounted forrelative turning movement about a common horizontal axis extendingtransversely of the hulls, a pair of elements, one adapted to be fixedto each hull, respectively, pivot means connecting each trunnion to oneof said elements, respectively, for pivotal movement about verticalaxes, said second connector assembly including a transverse spacerstrut, a pair of elements, one adapted to be fixed to each hullrespectively, universal joints connecting the ends of said strut to thelatter said elements, respectively, a central member provided forsupporting said trunnions for relative turning movement, alongitudinally extending tubular post mounted on said spacer strut andslidably received within a socket member on said central member, andwherein a torsion bar extending within said post is connected atlongitudinally spaced locations to said central member and to said post.

8. Linkage for connecting twin hulls of a catamaran, comprising, incombination: first and second laterally extending longitudinally spacedconnector assemblies adapt- .ed to extend horizontally between thehulls; said first connector assembly including a pair of trunnionsmounted for relative turning movement about a common horizontal axisextending transversely of the bulls, a pair of elements, one adapted tobe fixed to each hull, respectively, pivot means connecting eachtrunnion to one of said elements, respectively, for pivotal movementabout vertical axes, said second connector assembly including atransverse spacer strut, a pair of elements, one adapted to be fixed toeach hull, respectively, universal joints connecting the ends of saidstrut to the latter said elements, respectively, a central memberconnected to, said trunnions and wherein means including alongitudinally extending torsion bar operatively connects said memberand said spacer strut.

9. Linkage for connecting twin hulls, comprising, in combination: firstand second connector assemblies extending between said hulls; said firstconnector assembly having axially aligned trunnions each connected bymeans of a vertical pivot to one of the said hulls, respectively, andmounting means for said trunnions whereby the hulls are permitted tohave relative pitching movehulls toward each other in a horizontal planeas a result ment and are prevented from having substantial relative ofparallel angular rotation of the said connector assemrolling movement;said second connector assembly havblies relative to said hulls isprevented.

ing a transverse spacer strut, and universal joint means connecting theends of said strut to said hulls; a central 5 References Cited In thefile of thls Patent member supported upon said trunnion mounting means;UNITED STATES PATENTS and longitudinal pivot means connecting the saidstrut 2,119,775 chase June 7 1938 and said member whereby relativemovement of the said

